Many-body correlations govern a variety of important quantum phenomena such as the emergence of superconductivity and magnetism. Understanding quantum many-body systems is thus one of the central goals of modern sciences. Here we demonstrate an experimental approach towards this goal by utilizing an ultracold Rydberg gas generated with a broadband picosecond laser pulse. We follow the ultrafast evolution of its electronic coherence by time-domain Ramsey interferometry with attosecond precision. The observed electronic coherence shows an ultrafast oscillation with a period of 1 femtosecond, whose phase shift on the attosecond timescale is consistent with many-body correlations among Rydberg atoms beyond mean-field approximations. This coherent and ultrafast many-body dynamics is actively controlled by tuning the orbital size and population of the Rydberg state, as well as the mean atomic distance. Our approach will offer a versatile platform to observe and manipulate non-equilibrium dynamics of quantum many-body systems on the ultrafast timescale.

Molecules are expected to be promising information devices 1-8. Theoretical proposals have been made for logic gates with a molecular wave packet modulated by a strong femtosecond laser pulse 9-15. However, it has not yet been observed how this changes the population of each eigenstate within the wave packet. Here we demonstrate direct observation of the population beating clearly as a function of the delay of the strong laser pulse. The period is close to the recurrence period of the wave packet, even though a single eigenstate should have no information on the wave-packet motion. This unusual beat arises from quantum interference among multiple eigenstates combined on a single eigenstate. This new concept, which we refer to as 'strong-laser-induced interference', is not specific to molecular eigenstates, but universal to the superposition of any eigenstates in a variety of quantum systems, being a new tool for quantum logic gates, and providing a new method to manipulate wave packets with femtosecond laser pulses in general applications of coherent control 16-20. The wavefunctions of electrically neutral systems can replace electric charges of the present Si-based circuits, whose further downsizing will soon reach its limit where current leakage will cause heat and errors with insulators thinned to atomic levels 21. Atoms and molecules are promising candidates for these neutral systems, in which the population and phase of each eigenstate serve as carriers of information 1,2,22,23. A shaped ultrashort laser pulse can access many eigenstates simultaneously within a single atom or molecule, manipulating the amplitude and phase of each eigenstate individually to write more than one million distinct binary codes in the angstrom space 1,2. Molecules in particular are now expected to be promising components to develop scalable quantum computers 5-8. The development of I /O and logic gates with molecules should be meaningful for us to be prepared for such a future scalable system. It is therefore important to study information processing with molecular eigenstates for both high-density classical information processing and quantum information processing. This background has motivated us to propose molecular eigenstate-based information processing (MEIP), and to demonstrate the ultrafast Fourier transform based on the temporal evolution of a molecular wave packet 2-4. For more universal computing in MEIP, however, one should consider another class of logic gates with a strong femtosecond laser pulse whose broad bandwidth and high intensity allow for multiple transitions among different eigenstates within a wave packet simultaneously. This scheme has been employed in a number of theoretical studies on MEIP logic gates 9-15 , and also in a few experimental studies 24 , but it has not yet been observed experimentally how each eigenstate changes its population with those multiple transitions within a wave packet. Here, we report the direct observation of the population of each vibrational eigenstate within a wave packet mod...

The formation of Ar and H2 clusters, having up to 900 particles in helium droplets, has been studied via laser induced fluorescence of attached Mg-phthalocyanine (Mg-Pc) molecules. In the experiments, one Mg-Pc molecule in average was added to each He droplet either before or after the cluster species, and the shift of the spectrum of the Mg-Pc molecules was studied as a function of the cluster size. For Ar clusters, about a factor of 2 smaller matrix shift was observed for the late pickup of the Mg-Pc molecules as compared with the prior pickup, indicating that in the former case, the Mg-Pc molecules reside on the surface of the preformed Ar clusters. On the other hand, the spectra of the Mg-Pc molecules attached to H2 clusters are independent of the pickup order, which is consistent with Mg-Pc molecules residing near the center of the H2 clusters in both cases. Therefore H2 clusters remain fluxional in helium droplets at T=0.38 K. No significant differences in the spectra were observed between the para-H2 and ortho-H2 clusters.

A modified alkaline nitrobenzene oxidation (NBO) method was developed to enable the analysis of the biphenyl structures of cedar wood lignin. The most essential point of the process is a modified work-up process in pyridine and a prolonged gas chromatography analysis of the silylated products. By applying this mean to cedar wood meal, a novel biphenyl product, dehydrovanillin-vanillic acid (1-carboxy-1′-formyl-4,4′-dihydroxy-3,3′-dimethoxy-5,5′-biphenyl), was detected together with known products, dehydrodivanillin and dehydrodivanillic acid. The highest total yield of biphenyl products was detected when NBO was carried out for 2-4 h at 170°C. The workup procedure was slightly modified so that the biphenyl products can be quantified. The NBO conversion rates of biphenyl linkages of lignin were also examined with a biphenyl-type lignin model compound, and this gave rise to 75% biphenyl-type NBO degradation products. Under the same condition, the total yield of vanillin and vanillic acid (VA) from a non-condensed-type β-O-4 model compound was 89%. Because the latter did not exhibit any peak of the biphenyl products, it can be concluded that all the biphenyl products obtained by NBO (0.17 mmol g -1 ) were from the lignin of the native wood. It was calculated that at least 6.7 of 100 phenylpropanoid units of cedar lignin were involved in biphenyl structures even if the NBO conversion rate was not taken into consideration. The synthesis and analytical data of 11 lignin model compounds is described.

Background Evidence of factors associated with psoriasis from large population-based cohort studies is scarce. Objective We aimed to explore the risk factors of late-onset psoriasis. Methods This study included 487,835 Japanese participants aged 40-107 years, who were followed prospectively from 2012 to 2018 using individually linked databases between annual health checkups and medical claims. Results During the study period, 2793 patients (0.57%) newly developed psoriasis; 13.8% had moderate-to-severe psoriasis. In the multivariate analysis, factors associated with psoriasis onset were age (hazard ratio [HR] 1.11 {95% confidence interval [CI]: 1.06-1.16}), male sex (HR: 1.11 [95% CI: 1.02-1.21]), body mass index (HR: 1.09 [95% CI: 1.05-1.14]), smoking (HR: 1.46 [95% CI: 1.31-1.63]), not exercising ≥1 hour per week (HR: 1.13 [95% CI: 1.05-1.22]), and gamma-glutamyl transpeptidase (HR: 1.04 [95% CI: 1.01-1.06]). When we used weight increment of ≥10 kg since the age of 20 years instead of body mass index in the multivariate model, this was also a risk factor (HR: 1.12 [95% CI: 1.04-1.21]). Limitations This study targeted people aged >40 years, thereby narrowing the search to the risk factors of late-onset psoriasis. Conclusion We showed that increasing age, male sex, body mass index, smoking, low physical activity, weight gain, and gamma-glutamyl transpeptidase are associated with late-onset development of psoriasis and revealed a relationship between liver dysfunction and psoriasis development.

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